There's a lot of truth in that, but it's not strictly true. The Obama DOJ pursued and enforced consent decrees over a bunch of local police departments; the incoming Republican DOJ announced that they were backing away from them. Certainly, national politics has some influence over local policing.

But I'm mostly with you. I'm kind of dumbfounded by how much attention gets paid to national/federal policing policy, where change is essentially impossible to achieve, when most people live in suburbs, where 2-3 seats on a village or township board can result in nearly arbitrary policing policy changes for that suburb. Swing House seats are a million-dollar proposition; a village board seat in Oak Park might go for less than $5000 invested.

A serious theory of change, and one I think more credible than passing any kind of new federal law: get reformer village boards elected in a scattering of suburbs, get them to pass sharp, meaningful policies (an end to no-knocks, crisis intervention teams, or dream big and have the police stop doing routine traffic enforcement), then prove them out. I've been watching Chicagoland village board meetings for the past couple months, and the modal question that seems to come in policy discussions is "what are the neighboring suburbs doing". Start there! See if you can get a snowball rolling.